As data storage systems increase in size and complexity, their management becomes increasingly onerous. In addition to routine maintenance, which may includes alterations to the system such as installing, upgrading or removing software and hardware, there is the maintenance required to deal with emergencies, such as a failure of a part of the system. A number of processes are available to help administrators perform the system management.
U.S. Pat. No. 6,088,766 to Bachmat et al, whose disclosure is incorporated herein by reference, describes a process for load balancing of activities on storage devices by monitoring reading and writing to blocks of the devices. As described in the disclosure, statistics derived from such monitoring may be used to decide whether reallocation or exchange of a pair of physical volumes is made.
U.S. Pat. No. 6,496,850 to Bowman-Amuah, whose disclosure is incorporated herein by reference, describes a process for determining an “orphaned server context.” The process maintains a list of contexts of outstanding server objects, and of clients interested in the contexts. The list is examined at predetermined times to determine if a context has been accessed by a client, and those that have not been accessed within the time are provided to the clients.
U.S. Pat. No. 6,415,372 to Zakai et al, whose disclosure is incorporated herein by reference, describes a system for reconfiguring a storage system, and for rolling back a configuration of a storage system to an earlier configuration. The disclosure states that rolling back configurations can help system managers who wish to experiment with different configurations. The disclosure further states that a system manager may make a tentative reconfiguration, and roll back to an earlier configuration if the new configuration does not improve performance.
U.S. Pat. No. 5,835,953 to Ohran, whose disclosure is incorporated herein by reference, describes a system that maintains logically consistent backups. A primary system identifies changes that are to be made in a mass storage device, and captures a static snapshot of locations where changes are to be made in the device when it is in a logically consistent state. The snapshot is used to facilitate the backup of data blocks to be changed.
U.S. Pat. No. 6,209,059 to Ofer et al, whose disclosure is incorporated herein by reference, describes a method for on-line reconfiguration of logical volumes of a storage system. A new configuration is defined by rearranging a request queue, and redefining devices of the system within the queue. The rearrangement and redefinition occur while the current configuration operates. The system may be operated in accordance with the new configuration once it is defined.
U.S. Pat. No. 6,237,000 to Dahlen et al, whose disclosure is incorporated herein by reference, describes a system for previewing results of a data structure allocation. A coupling facility receives a message containing parameters defining a data structure. The facility returns a message giving values of the data structure without actually allocating the data structure.
U.S. Pat. No. 3,702,006 to Page, whose disclosure is incorporated herein by reference, describes a method for balancing I/O devices. During operation of a processing system, a count is made of a number of times each I/O device of the system is accessed by each task of the system. An estimated current utilization and an anticipated utilization are compared so as to allocate data sets to a least used I/O device.
U.S. Pat. No. 5,515,499 to Allen et al, whose disclosure is incorporated herein by reference, describes a method for rebuilding a structure located in a data processing system. A connection is made to a first structure having one or more predefined characteristics. The first structure has a name. A second structure having the same name as the first structure is allocated. The second structure has one or more predefined characteristics different from the first structure. The disclosure states that the second structure may be used for planned system reconfigurations or for recovery from system failures.
U.S. Pat. No. 5,574,851 to Rathunde, whose disclosure is incorporated herein by reference, describes an architecture for on-line reconfiguration of a Redundant Array of Independent Disks (RAID). The architecture allows the reconfiguration to be performed in a sequential manner, while disk I/O operations continue.
U.S. Pat. No. 6,546,457 to Don et al, whose disclosure is incorporated herein by reference, describes a system for reconfiguring striped disks in a storage array. A copy of one of the devices in the array is made in parallel with host operations. A logical device with a new configuration is then substituted for access by the host.
U.S. Pat. No. 5,220,654 to Benson et al, whose disclosure is incorporated herein by reference, describes a serialization technique for changing an I/O configuration. The technique insures that data integrity is not lost on devices being reconfigured, and that changes to control structures are noticed by programs accessing the structures while the structures change.